The present invention relates to a process for the preparation of cyclooctene by hydrogenating 1,5-cyclooctadiene. More particularly, it relates to a process for the preparation of cyclooctene by partially hydrogenating 1,5-cyclooctadiene photochemically by the use of an alcohol as a hydrogen source.
The inventors of the present invention previously found that the Wilkinson complex (see Japanese Patent Publication No. 59-4406}and rhodium compounds (see Japanese Patent Publication No. 60-329) exhibited a remarkably high photocatalytic dehydrogenation activity on 2-propanol in the air, thus accomplishing the inventions relating to photodehydrogenation catalysts. Further, the inventors advanced their studies to find an efficient process for the preparation of ethylene glycol by irradiating methanol with light in the presence of both acetone and a rhodium complex (see Japanese Patent Publication No. 60-6930). In this process, acetone absorbs the light falling thereon to advance the reaction, i.e., acetone functions as a photosensitizer, so that methanol itself need not absorb the falling light.
The inventors of the present invention have made studies on a process for simultaneously conducting the dehydrogenation of a hydrogen source and the hydrogenation of an unsaturated compound by utilizing such a photodehydrogenation catalyst and have accomplished the present invention.
Cyclooctene which is the product of the present invention is one of the important intermediates for the preparation of synthetic resins by metathesis or oxidative ring opening.